1/*
2 * Copyright (C) 2010 Google Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.clearsilver.jsilver.output;
18
19/**
20 * Implementation of OutputBufferProvider that reuses the same StringBuilder in each Thread.
21 */
22public class ThreadLocalOutputBufferProvider implements OutputBufferProvider {
23
24  private final ThreadLocal<StringBuilder> pool;
25  private final ThreadLocal<Boolean> available;
26
27  public ThreadLocalOutputBufferProvider(final int bufferSize) {
28    pool = new ThreadLocal<StringBuilder>() {
29      protected StringBuilder initialValue() {
30        return new StringBuilder(bufferSize);
31      }
32    };
33    available = new ThreadLocal<Boolean>() {
34      protected Boolean initialValue() {
35        return true;
36      }
37    };
38  }
39
40  @Override
41  public Appendable get() {
42    if (!available.get()) {
43      throw new IllegalStateException("Thread buffer is not free.");
44    }
45    StringBuilder sb = pool.get();
46    available.set(false);
47    sb.setLength(0);
48    return sb;
49  }
50
51  @Override
52  public void release(Appendable buffer) {
53    if (buffer != pool.get()) {
54      throw new IllegalArgumentException("Can't release buffer that does not "
55          + "correspond to this thread.");
56    }
57    available.set(true);
58  }
59}
60